1. Field of the Invention
The present invention relates to an optical device such as a spectrophotometer or a detector for a liquid chromatography.
2. Description of the Related Art
In a related art, a spectrophotometer comprises a light source section for irradiating a sample to be measured with light, a sample section for holding a sample to be measured and ensuring light irradiation, a spectral section for dispersing light transmitting the sample, a measuring section for measuring an intensity distribution state etc. of the dispersed light, and a control section for driving signals of this measuring section.
Specifically, it is configured as shown in FIG. 2. A configuration of the related-art spectrophotometer and configurations and function of a measuring section and a control section will be described below by this FIG. 2 and Table 1 showing measurement steps. In FIG. 2, numeral 1 is a halogen lamp, and numeral 2 is a deuterium lamp. Light from both the lamps 1, 2 is switched by a switching plate 3 and a sample compartment 5 is irradiated with the light through a lens 4. Portions to this irradiation system construct a light source section. The light from the light source section passes through a lens 6 and is led to a grating 8 via an inlet slit 7 and is dispersed. A spectral section is constructed of the lens 6, the inlet slit 7, the grating 8 and so on. The dispersed light is detected by a spectrometric detector 9. Incidentally, the spectrometric detector 9 is constructed of a multi-channel serial readout type of device such as a self-scanned photodiode array. Then, an output from this spectrometric detector 9 is inputted to a measuring section M comprising a signal processing circuit 10, an A/D converter 11, a DSP (digital signal processor) 12 and a detector driving circuit 13. Further, this measuring section M is connected to a control section C comprising a CPU (central processing unit) 14, an external signal detection circuit 15 and a PC (personal computer) 16. Also, the control section C is connected to an external device 17 of the outside and is remotely controlled specifically.
Next, measurement by this spectrophotometer will be described specifically. Light generated in the deuterium lamp 2 which is a lamp for detection passes through the switching plate 3 and the lens 4, and receives light absorption by a sample (not shown) inside the sample compartment 5, and is read out of the spectrometric detector 9 as an intensity distribution signal (hereinafter called data). In FIG. 2, the switching plate 3 shows the case of a half mirror, but has a structure capable of performing switching of three kinds of a shutter of light blocking, a half mirror for superimposing light of the halogen lamp 1 and the deuterium lamp 2, a through for passing through only light of the deuterium lamp 2 for any purpose. As necessary, by switching of the switching plate 3, the light from the deuterium lamp 2 is led to the spectrometric detector 9 and an emission line wavelength is detected to define a wavelength.
In a measurement start of the spectrophotometer, there are the case that a measurer inputs a measurement start signal to the spectrophotometer by a keyboard operation directly and the case that a measurement start signal is inputted from the external device 17 of the outside of the spectrophotometer after a measurer inputs measurement standby instructions to the spectrophotometer. As shown in Table 1, at a point in time of measurement standby instruction input, the measuring section M is in a self-scanned state (readout state). Once the measuring section M shifts to the self-scanned state, data readout processing from the spectrometric detector 9 has precedence over instructions from the control section C, so that the data readout from the spectrometric detector 9 cannot be suspended on the way.
A function (hereinafter called a monitoring function) of monitoring and detecting a measurement start signal (hereinafter called an external start signal) given from the external device 17 present in the outside of the spectrophotometer is provided inside the control section C. Since the monitoring function acts periodically, there is a period during which monitoring stops. In a measurement standby state, the measuring section M is in a self-scanned state of periodically repeatedly reading data out of the spectrometric detector independently of the external start signal. Steps (action outline) of the case that the external start signal outputted by the external device 17 is inputted to the spectrophotometer and measurement using the external start signal as a starting point is made are shown in Table 1.
TABLE 1ExternalControlMeasuringStepEventsection Csection M1MeasurementSelf-StandbyscannedInstructionStateWait State2MeasurementMeasurementStandbyStandbyInstructionInstructionInputDetection3Transition toMonitoringState4InstructMeasuringsection M onTransition toMeasurementState5ExternalExternalTransition toStart SignalStart SignalMeasurementInputDetectionState6Transition toDataReceivingWait StatefromMeasuringsection M7Transition toDataProcessingState8Return toReturn toMeasurementSelf-StandbyscannedInstructionStateWait State
That is, in Table 1, steps 1 to 4 are measurement standby steps, and step 5 and subsequent steps are measurement steps using an external start signal as a starting point. In steps 1 to 4, the measuring section M is in a self-scanned state, and data is periodically repeatedly readout of the spectrometric detector 9 anytime every period of a readout start signal and a readout clock (hereinafter collectively called a readout signal) outputted to the spectrometric detector 9, and the data is repeatedly stored for a certain time (hereinafter called storage time) which is shorter than or equal to the period of the readout signal, but is not outputted until step 7. The external start signal is inputted from the external device 17 to the external signal detection circuit 15 and a control signal (instructions on transition to a measurement state) is outputted. Incidentally, in Table 1, an external start signal is inputted after measurement standby instruction input, but in some cases, a spectrophotometer independently may start measurement of change with time before the external device 17 acts. A related-art spectrophotometer does not have a function of setting wait time from an external start signal to an actual measurement start.
In Table 1, “measurement standby instruction wait state” means a state of waiting for input of measurement standby instructions by a measurer from a panel key etc. of a spectrophotometer or software of the PC 16 of FIG. 2, and “monitoring state” means a state of waiting for an external start signal of FIG. 2. Also, “data receiving wait state” means a state in which it is checked whether or not there is data sent from the measuring section M and if so, readout of data, calculation of data, temporary retention, display and sending of data are performed, and in parallel with that, a state of periodically monitoring whether or not to satisfy conditions for ending a measurement action, for example, whether or not time specified by a measurer has elapsed since a measurement start and whether or not a measurer has instructed a measurement end by inputting a signal from a key allocated to the measurement end, etc., and “self-scanned state” means a state in which readout data from the spectrometric detector 9 is regarded as invalid and is not outputted although a readout signal is outputted to the spectrometric detector 9 of FIG. 2. Then, “measurement state” means a state in which a readout signal is outputted to the spectrometric detector 9 and readout data from the spectrometric detector 9 is regarded as valid and is outputted.
The configuration and function of the related-art spectrophotometer are described above. In the related-art spectrophotometer, once the measuring section M shifts to a readout state, data readout processing from the spectrometric detector 9 has precedence over instructions from the control section C, so that the readout cannot be suspended on the way. As a result of that, generation time of a control signal cannot be synchronized with generation time of some readout signal repeated periodically. The first data after output of the control signal is discarded because there is a possibility that storage is started before the generation time of the control signal, and the second or below data is outputted, but indefinite delay time due to the a synchronism described above occurs, so that time of a difference between start time of storage of the second data and the generation time of the control signal cannot be defined. As described above, even in a measurement standby instruction wait state, readout is performed anytime, so that in the case of presetting short storage time (a readout clock of a short period) in order to observe a rapid change in time, the number of data per unit time increases and valid measurable time decreases due to capacity etc. of a memory device and a memory element inside a DSP. Also, when the spectrophotometer independently starts measurement of change with time before the external device 17 acts, there is a need for processing in which while a measurer observes the degree of change in measured data after the end of measurement, the time origin is presumed and unnecessary data before the external device 17 acts is discarded.